The present invention relates generally to a fiber containing mixture and method for producing a fracture-resistant, fiber-reinforced ceramic material by the use of microwave heating.
Conventional manufacture of ceramics has been done by the use of resistant heating furnaces, which consume relatively large quantities of energy, time, and manpower while subjecting the ceramics to rather hostile environments. An alternative method of producing ceramic material used in seals was disclosed in U.S. Pat. No. 4,529,856 and U.S. Pat. No. 4,528,857 for "Ceramic-Glass-Metal Seal By Microwave Heating" and "Ceramic-Glass-Ceramic Seal By Microwave Heating" respectively. The ceramic materials used in the seals were formed by subjecting a slurry comprising a coupling agent, such as watch oil, and a sealing material, such as glass, evenly spread between the ceramic and ceramic or metal substrates, to microwave energy in order to cause heating and formation of the seal. An additional method and mixture for making ceramic materials, also used in seals, was disclosed in U.S. Pat. No. 4,606,748. This other method consisted of subjecting a mixture of glass sealing material, a coupling agent, and an oxidizer to microwave radiation which heated the mixture, sufficiently to ignite the oxidizer and to cause a liquid-phase seal to form.
Problems still remained with the ceramic materials formed even by these new microwave heating processes. Specifically, when ceramic materials were produced in shapes larger than about 4".times.4" (10 cm.times.10 cm), fractures would result. Additionally, the ceramic materials produced both by the microwave heating process and by conventional processes, could not be modified in such a way that the heat built up either in or on the ceramic substrate could be dissipated in a geometrically controlled manner. Finally, the ceramic materials had no special shunt capacitance values that would allow quicker transit times for electronic pulses in any conducting pathways established on the ceramic substrates.
Therefore, it is an object of the present invention to provide an improved method of forming ceramic substrates which have greater fracture resistance in larger geometric shapes.
It is the further object of the present invention to provide an easily automated, low energy, efficient, fast, and effective method for forming ceramic substrates with increased strength.
It is yet another object of the present invention to provide a ceramic substrate in which the dissipation of heat produced in or on the substrate can be geometrically controlled.
Finally, it is another object of the present invention to provide a ceramic substrate with a shunt capacitance value such that electronic pulses in established conducting pathways have quicker transit times.